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Expansions and Accessories
6.1.5.7
Bus cable
To meet ISO 898, a bus cable with a characteristic impedance of 120 W should be used.
The maximum usable cable length for reliable communication decreases with increasing
transmission speed. As a guide, you can use the following values which we have measu-
red, but they are not to be taken as assured limits.
General characteristic
Bit rates
Distance with larger
bus connections
Number of nodes
Signal environment
Modulation
Coupling medium
Isolation
Typical differential input im-
pedance (recessive state)
Min. differential input impe-
dance (recessive state)
Absolute max.
voltage range
Grounding:
The DeviceNet network must only be grounded at one point, to avoid ground loops. The
circuitry for the physical layer in all devices are referenced to the V-bus signal. The
ground connection is made via the power supply for the bus system. The current flowing
between V- and ground must not flow through any device other than the power supply.
Bus topology:
The DeviceNet medium utilizes a linear bus topology. Termination resistors are required
at each end of the connecting cable. Stub cables are permitted up to a length of 6 meters,
so that at least one node can be connected.
Termination resistors:
DeviceNet requires a termination at each end of the connecting cable.
These resistors must meet the following requirements: 120W, 1% metal-film, 1/4 W
84
12/05
Specification
125 kbit, 250 kbit, 500 kbit
500 meters at 125 kBaud
250 meters at 250 kBaud
100 meters at 500 kBaud
64
CAN
Basic bandwidth
DC-coupled differential transmit/receive operation
500 V (option: optocoupler on the transceiver's node side)
Shunt C = 5pF
Shunt R = 25KW (power on)
Shunt C = 24pF + 36 pF/m of the permanently
Shunt R = 20KW
-25 V to +18 V (CAN_H, CAN_L)
The voltages for CAN_H and CAN_L refer to the ground pin
of the transceiver. The voltage is higher than that on the
V-terminal by the amount of the forward voltage drop of the
Schottky diode. This voltage drop must be < 0.6V.
SERVOSTAR
Kollmorgen
attached stub cable
®
300 Installation Manual
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